Propelling mechanism for vehicles.



A. BOYD. PROPELLING MECHANISM FOR VEHICLES.

APPLICATION FILED AUG. 6, 1914,

Patented Feb. 2, 1915.

5'-SHEETSSHEET 1.

A. BOYD.

PROPBLLING MECHANISM FOR VEHICLES.

APPLICATION FILED AUG. 6, 1914. 1 1 26,947. Patented Feb. 2, 1915.

5 SHEETS-SHEET 2.

HE NORRIS PETERS (20.. PHOTO-LITHQ, waSHuvuluN, D.

A. BOYD.

PROPELLING MECHANISM FOR VEHICLES.

APPLICATION FILED AUG. 6, 1914.

atented Feb. 2, 1915.

5 SHEETS-SHEET 3.

HE NORRIS PETERS Co.. PHOT A. BOYD.

PROPELLING MECHANISM FOR VEHICLES.

APPLICATION FILED AUG. 6, 1914.

Patented Feb.2, 1915.

5 SHEETSSHEET 4.

A. BOYD.

PROPELLING MECHANISM FOR VEHIGLES.

APPLICATION FILED AUG.6,1914.

Patented Feb. 2, 1915.

5 SHEETS-SHEET 5.

Q mu UN HE NORRIS PETERS cu PHOTO-LITHQ. WASHINGTON, D r

UEHTE ARTHUR BOYD, OF WEST HARTLEPCOL, ENGLAND.

PROPELLING MECHANISM FOR VEHICLEEa.

Specification of Letters Patent.

Patented Feb. 2, 1&15.

Application filed August 6, 1814. Serial No. 855,418.

To all coil mt it may concern Be it known that 1, ARTHUR BOYD, a subject of the King of Great Britain and Ireland, residing at West Hartlepool, in the county of Durham, England, have invented certain new and useful improvements in Propelling Mechanism for Vehicles; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the propulsion of bicycles and is intended to efiect improvements in the means employed for obtaining increased leverage or turning moment of the crank arm or pin of a pedal driven bicycle or the like when the said crank arm or pin is on or approaching the lower dead center during the power giving stroke, the effect being carried through a considerable portion of the stroke.

1n the accompanying drawings, Figure 1 shows a side elevation of so much of the crank mechanism of a bicycle as is necessary to illustrate one embodiment of my invention, some of the parts being shown in various positions by dotted lines. Fig. 2 shows a front elevation of the same with some parts broken away. Fig. 3 is a view similar to Fig. 1 of a modification. Fi 4: is a view similar to Fig. of the modii'cation shown in Fig. 3. Fig. i is a detail view in section on the line cc-m of Fig. 1. Figs. 5 and 6 are views similar to Figs. 1 and 2 of another modification. Fig. 6 is a detail view in section on the line wr0 of Fig. 6. Fig. 6 is a detail View in section on the line 1 i of Fig. 6. Figs. 7 and 8 are views similar to Figs. 1 and 2 of still another modification. Figs. 8, 8 and 8 are detail views of parts of the mechanism shown in Figs. 7 and 8.

In the several figures of the drawings a indicates the upper crank arm, and b the opposite crank arm, shown in position of approaching the lower dead center where the leverage is diminishing until it vanishes when the crank arrives at position 19 shown in dotted lines; at the same time the crank a arrives at position a where it attains considerable leverage for the working stroke.

Referring to Figs. 1 and 2, in which the crank pin 0 is hollow, 0 is the spindle working within it as a bearing, the ratchet 0 being a fixture to the said spindle c and abutting against the hollow crank pin 0, the

are common to all the modifications andforms of mechanism as illustrated in Figs. 1 to 6". On further referring to Figs. 1 and 9., the mechanism used for reducing this angular velocity of the ratchet wheel for causing the interlock as required for the purpose of my invention consists mainly of a combination or sprocket wheels and their endless chain connection. A sprocket wheel 7 is affixed to the hub or crank bracket of the machine as a dead wheel and a larger sprocket wheel f is ailixed to the ratchet spindle 0 the two sprocket wheels f 7 being geared together by the endless chain f this arrangement being similarly applied to both cranks, the ratchet wheel 0 being clutched by the pedal by means of the pawl e which is sustained in the operative position by the spring 6 with the result that the angular velocity of the ratchet wheel is reduced in the ratio of the eliective diameters of these two sprocket wheels that is to say that if the diameter of the sprocket wheel f on the ratchet spindle 0 is twice that of the sprocket wheel on the crank bracket hub the angular velocity of the spindle 0 will be reduced to one half of that of the hollow crank pin and suitable to the available angular movement of the pedal or foot.

In the modification shown in Figs. 3, 1, and 1 most of the parts shown are similar to those indicated in Figs. 1 and 2, and such parts are similarly lettered. Instead of the sprocket wheel and chain gearing shown in Figs. 1 and 2, toothed wheel gearing is used, a toothed wheel 79 being rigidly fixed to the bottom or crank bracket as before. A. spur wheel 79 of larger diameter is rigidly fixed to the ratchet wheel spindle 0 working in the hol ow crank pin 0 and an idle or intermediate wheel 39 for changing the direction of the motion of the spur wheel p is pivoted to and carried on the crank arm 6, the said idle wheel being of any suitable diameter to make up the distance between the dead wheel 7) and the spur wheel 22 with the result that as the pedal is depressed in the direction of the arrow 1 (Fig. 3) the pawls g on the pedal d engage the internal ratchet teeth of wheel and the pedal now assumes for the time being the reduced angular velocity of the internal ratchet wheel g which is suitable to the available velocity of the foot, and corresponding to the ratio of the effective diameters of the Wheels 39 and 7) as before.

In the Figs. 5, 6, 6 and 6, another cog wheel modification is shown. In this construction the spindle a working within the hollow crank pin 0 is an integral part of the spur wheel r as before and is furnished with an internally toothed wheel 9 squared on its outer end in the place of the ratchet wheel. The ratchet wheel 1 in this case is arranged to rotate within the recess in the pedal and upon the hollow crank pin as an axis and carries four speed pinions which are pivoted on to the face of the ratchet wheel 9" to gear with the internally toothed dead wheel g, and these pinions g are adapted to be driven by the pedal by means of pawls c 0 attached to the internal periphery of the pedal chamber 71., which pawls engage with the ratchet wheel when the pedal is angled or depressed as required. These four speed pinions 9 also gear with a pinion g secured as a fixture to the hollow crank pin 0 with the result that when the pedal is angled the ratchet wheel pinions g are driven under the teeth of the dead wheel 9 and also simultaneously over the teeth of the central pinion g on the hollow crank pin as fast as the pinion on the crank pin will allow as is well known in speed gears so that at any time the pedal can angle with half the angular velocity of the hollow crank pin or other velocity depending on the size of wheels used or have at any other time what is known technically as a motion of circumduction while the pinions revolve idly by reason of the revolution of the fixed pinion g" on hollow crank pin 0. The rest of the gearing consisting of an idle toothed wheel r and a crank bracket or hub toothed dead wheel r is the same as in the modification already described with reference to Figs. 3, a: and a except that the dead wheel 4" on the crank bracket hub and the spur wheel 1 on the spindle c in the hollow crank pin 0 have equal effective diameters with any diameter of idle wheel r between to make up the distance with the result that the spur wheel r and. therefore the internally toothed wheel 9 on the spindle c are now both dead wheels or have a motion of circumduction only when the machine is in motion and upon the latter of which the speed gear pinions can act.

A further modification and one which may be considered desirable in practice is illustrated in Figs. 7 to 8 inclusivep In the modified arrangement of speed reducing mechanism comprised in these figures the principle of the eccentric is embodied and what is known as a wrist plate which takes the place of the spindle working within the hollow crank pin. In these figures,

m. The wrist plate which is under the con-- trol of the fixed or dead eccentric 7c is shown in the form of a circularbox, and is furnished with pawls 8 within its outer rim which are engaged by the teeth of a ratchet wheel .9 centered and working upon the boss m surrounding the boss 2' of the crank arm a in to which boss the crank pin 0 is screwed; 0 being a flange on crank pin 0 for bearing surface purposes. The ratchet wheel a has projections 02 pitched around the boss of the ratchet wheel 3 and extending outwardly towardthe pedal (Z to be engaged by corresponding projections 11. on the boss of the pedal d in the form ofa claw clutch, with the result that as the pawls in the wrist plate move with less angular velocity than the crank pin 0 under the action of the eccentric rod Z when the crank is approaching the lower half of the working stroke the pedal can turn the ratchet wheel s and its teeth overtake the pawls s in the wrist plate m and therefore the pedal takes up the reduced velocity of the wrist plate as required, the pedal being thus locked to the wrist plate or clutch box m, with the result that while the spur gears shown in Figs. 1 to 6 are'in constant ratio, the device shown in Figs. 7 to 8 is constantly varying although the crank shaft may be moving with uniform angular velocity throughout the revolution. In these Figs. 7 to 8, k are eccentrics one on each end of the crank bracket boss orhub and fianged together by bolts and embracing the crank bracket boss where practicable. Z is the eccentric rod surrounding the eccentric 70 on a ball race.

The outer extremity of the rod Z is coupled by a ball bearing to the crank pin m on the back of the wrist plate m and the aforesaid eccentric rod Z on the chain wheel side of the machine is bent to pass through the chain. wheel to reach the crank pin m on the wrist plate but the rod could be more directly connected by dishing the chain wheel out as shown in Figs. 2, 4 and 6, the eccentric being kept further out to-take the position of the dead wheel 7 shown in these figures.

Fig. 8 shows an interior view of the mechanism of the wrist plate m in the form of an annularly' shaped box with its screwed cover m removed and shows the pawls e and the ratchet wheel 8 centered thereon and having clutch projections n for engagement by the pedal. The radial eccentricity of the crank pin m from the center is made ire about equal to twice the eccentric throw of eccentric ls.

In the outside view of the expanded exremity of the crank arm as shown in Fig. 8 a central boss 2' is adapted for carrying the crank pin and into which the crank pin 0 is screwed as a fixture, the wrist plate m being workably fitted on the boss i as an axis the outer boundary or flange a of the annular recess of the crank arm being useful for housing the wrist plate and for structural strength.

There is a concentric slot or opening j through the back of the recess for the wrist plate crank pin m to project through to the back of the crank arm in order to conple up to the outer extremity of the eccentric rod. The slot j is made of such circumferential length as to accommodate the variable angular movements of the pin m relatively to the crank arm a.

The several parts having been devised and arranged above described their combined action consists as follows:-Assuming the crank a to be revolving at a uniform rate. the wrist plate m makes a constantly varying angular movement about the axis of the crank pin 0 under the control of the dead eccentric 7c actuating the wrist plate m by the crank pin m which is twice as far from the center of the crank pin as the cocentric throw and the angular velocity of the wrist plate we will be considerably less than that of the crank pin 0 during the last half of each working stroke. and correspond ngly greater as the crank approaches its upper dead center. That is to say the wrist plate with its pawls is revolving about its ax s (or crank pin centerl with only half of the angular velocity of the crank pin (when the pedal arrives at 45 below the ho izontal on the down st oke) so that when this pedal is dep essed by the to the ratchet wheel which it d i es. engages the pawls on the wrist plate and the fo ce is t ansm tted to the c ank arm as reouired for the purpose of this invent on. And this act on can onlv take place during the last half of the working stroke as dist nguished from the gears in the previous iirures and furthermo e this reduced an ular velocitv of the wr st p ate is constantl var ing. whereas in the chain and s ur wheel ears. it is constant throu hout the evo ut on in relation to the crank pin. The function of these gears is to p oduce his difference of angular veloc ty and ma be termed diffe ential gear and virtually reduce the angular velocitv of the crank pin on its axis by subplying a new member to work noon the crank p n as an axis having a reduced angular velocity upon which the pedal may hecome locked by angling the foot, and the advantages derived are as follows :(1). The working stroke of the crank is increased and carried beyond the lower dead center. (2). The opposite or upper crank is brought into a position effective for driving leverage before the lower crank is dead or out of QfiQCtlYQ leverage. (3). There is always one of the cranks available for turning the crank shaft. l). The tension on the driving chain is more uniform throughout the revolution and more power can be developed.

Having thus described my invention, what I desire to claim and secure by Letters Patent of the United States is 1. Propelling mechanism for velocipedes, comprising a crank bracket, a crank shaft mounted to rotate therein. a stationary gear member through which the shaft extends and which is secured to the bracket, a crank arm. a pedal pivotally mounted thereon. a clutch member geared to the gear member on the bracket. and a clutch member carried by the pedal.

2. Propelling mechanism for velocipedes, comprising a crank bracket, a crank shaft mounted to rotate there n. a stationary gear member secured to said bracket. a crank arm. a pedal pivotally mounted thereon. and pawl and ratchet clutch mechanism geared to the stationary gear member on the b acket and adapted to connect the pedal therewith.

3. Propelling mechanism for velocipedes, compris ng a crank b acket a crank shaft mounted to rotate therein. a stationary gear member secured to said brac et. a crank arm. a crank pin rigidly secured to the outer end of the crank arm. a spindle supported by said crank pin and adapted to turn relatively thereto. a pedal. pawl and ratchet mechanism interposed between the. pedal and the spindle. and gearingconnecting said s indle with the stationar gear member on the crank b acket.

4. Propelling mechanism for velocipedes, comprising a crank bracket, a crank shaft mounted to rotate therein, a stationary gear member secured to the bracket. a crank arm, a crank pin carried by the outer end thereof, a pedal mounted to turn on said crank pin, pawl and ratchet mechanism and s eed gearing connected with the pedal and gearing connecting said pawl and ratchet mechanism and speed gearing with the stationary gear member on the crank bracket.

In testimony whereof, T affix my signature, in presence of two witnesses.

ARTHUR BOYD.

Witnesses:

JoI-IN YVILLIAM WALTON, FREDERICK CORNER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Eatents,

Washington, D. G. 

